AMPS: Adaptable magnetic particle spectrometer for relativistic laser-plasma experiments

We present the design, magnetic field characterization, simulated response, and first experimental deployment of the Adaptable Magnetic Particle Spectrometer (AMPS) for broadband hot-electron diagnostics in laser-plasma experiments. AMPS uses a modular permanent-magnet assembly, adjustable entrance slit, and interchangeable detector holders to tune the trade-off between energy range, spectral resolution, and signal throughput. Three-dimensional magnetic fields calculated with Radia are benchmarked against Hall probe measurements and used in relativistic particle-tracing calculations to generate energy-position calibration curves for multiple detector and magnet geometries. In the configuration fielded at the Titan laser facility, the spectrometer provides electron spectral coverage from ∼125 keV to 70 MeV. Initial measurements from short-pulse irradiation of Cu wire targets show broadband electron spectra with MeV-scale effective temperatures. These results demonstrate the sensitivity of AMPS as a flexible diagnostic for resolving hot-electron distributions over a broad energy range suitable for relativistic short-pulse laser experiments. Future upgrades toward scintillator-based, high-repetition-rate operation are discussed.